Blood is a liquid tissue that includes red cells, white cells, corpuscles, and platelets dispersed in a liquid phase. The liquid phase is plasma, which includes acids, lipids, dissolved electrolytes, and proteins. One particular protein suspended in the liquid phase is fibrinogen. When bleeding occurs, the fibrinogen reacts with water and thrombin (an enzyme) to form fibrin, which is insoluble in blood and polymerizes to form clots.
In a wide variety of circumstances, animals, including humans, can suffer from bleeding due to wounds or during surgical procedures. In some circumstances, the bleeding is relatively minor, and normal blood clotting functions in addition to the application of simple first aid are all that is required. In other circumstances substantial bleeding can occur. These situations usually require specialized equipment and materials as well as personnel trained to administer appropriate aid.
In an effort to address the above-described problems, materials have been developed for controlling excessive bleeding. Topical Absorbable Hemostats (TAHs) are widely used in surgical applications. TAHs encompass products based on oxidized cellulose (OC), oxidized regenerated cellulose (ORC), gelatin, collagen, chitin, chitosan, etc. To improve the hemostatic performance, scaffolds based on the above materials can be combined with biologically-derived clotting factors, such as thrombin and fibrinogen.
Previously known TAH materials, such as gelatin, collagen, oxidized cellulose, and biologics, such as thrombin, fibrinogen, and other materials have been used, but each of these materials has limitations. Hemostatic devices containing biologics have special handling requirements in order to maintain the biologic activity. Safety is also a concern when using animal- or human-derived biologics due to contaminants or adverse immunological responses. For example, one type of prior art blood clotting materials are blood-derived proteins or enzymes, including fibrinogen and/or thrombin, which are expensive, need specialized storage conditions, and require extensive purification in order to eliminate the potential for transmission of blood-borne infections.
Published U.S. Patent Applications 2011/0060419, 2010/0268335, and 2010/0249927, all entitled “MEDICAL DEVICES WITH GALVANIC PARTICULATES”, which are incorporated herein by reference in their entirety for all purposes; describe implantable medical devices having galvanic particulates. However, these references do not disclose the use of the galvanic particulates with specific hemostatic scaffolds.
Hemostatic devices containing liquid thrombin have special handling requirements in order to maintain thrombin's biologic activity. For example, liquid thrombin requires refrigeration to maintain shelf-life stability. Safety is also a concern when using animal or human derived thrombin as there are some risks of contaminants or immunogenicity. Further, thrombin and fibrinogen purified from human or animal plasma are very expensive. Therefore, it is advantageous to develop novel hemostats that can provide improved hemostatic performance, preferably materials that are not derived from animal blood origins, but have comparable performance, long shelf life and ambient conditions of storage, and low cost. There is a need in hemostatic materials with greater shelf-life stability, lower risk of viral contaminants and lower immunogenicity, low cost, and which can work in heparinized or platelet inactivated blood.